Location-based services (LBS) have become an integral part of our daily life with applications including car navigation, location-based social networks, and context-aware predication and advertisement. Different LBS require different localization accuracies; Generally, GPS is considered the de facto standard for ubiquitous and accurate outdoor navigation. However, GPS is an energy-hungry technology that can drain the scarce battery resource of mobile devices quickly. In addition, its accuracy is limited in areas with obscured access to the satellites, e.g. in tunnels and many urban areas.
To address the high energy requirement of GPS-based localization, a number of outdoor localization systems have been proposed over the years (Ionut Constandache et. al. 2009, Ionut Constandache et. al. 2010, and Moustafa Youssef et. al. 2010). For example, city-wide WiFi and cellular-based localization systems depend on fingerprinting the WiFi and cellular networks through a war driving process to remove the need for GPS. Other systems, e.g. (Ionut Constandache et. al. 2010, and Moustafa Youssef et. al. 2010), depend on the inertial sensors in today's smartphones to obtain the location through a dead-reckoning approach and revert to GPS sampling with a low duty cycle to reset the accumulated localization error. However, this saving in energy usually comes at reduced localization accuracy, affecting the range of possible LBS. There is a need for efficient energy utilization devices for more accurate guiding systems.